Conventional Voice over Internet Protocol (VOIP) system architectures are tightly coupled to the legacy Public Switched Telephone Network (PSTN). Devices known as “media gateways” send or transfer a call from a packet-based network carrying the VoIP data, such as the Internet, to the circuit-based PSTN network. These media gateways focus on translating signaling information, call routing information, and voice payloads between the two different networks and relaying such information between the networks. Media gateways have a combination of circuit switched technology and packet switched technology, and their internal structure is typically architected around call routing technology based on elements of the legacy PSTN system.
Because these media gateways are tightly coupled to the PSTN, their implementation necessitates a highly distributed architecture with many attachment points to the PSTN. In fact, conventional VoIP architectures often use the PSTN as a backbone to connect these distributed attachment points together.